Is Mars Really That Similar to Earth?

Gale Crater on Mars, the landing site of the Mars Science Laboratory Curiosity rover. Photo courtesy of NASA/JPL-Caltech/ASU/UA.

Sep. 11, 2018

A study led by UNLV geoscientist Arya Udry shows that felsic rocks, rich in the element silicon, found on Mars’ Gale Crater are not similar to the Earth’s continental crust, and thus Mars may not be as Earth-like as previously suggested.

In an unexpected discovery, the Mars Science Laboratory Curiosity rover, which landed in Gale Crater in August 2012, found felsic rocks. On Earth, felsic rocks are very common, especially near plate boundaries. The Sierra Nevada mountain range, which mainly consists of granite, is an example of such lithology.

A previous study hypothesizes that these felsic rocks could indicate the presence of continental crust on Mars, a feature previously thought to be unique to Earth. Mars traditionally is believed to be covered in darker igneous rock similar to Earth’s oceanic crust. The discovery of felsic rocks on Marsled planetary scientists Arya Udry and Harry McSween from the University of Tennesseeto collaborate with terrestrial geologist Esteban Gazel from Cornell University to better constrain the magmatic similarities between Mars and Earth.

The research team used the thermodynamical software MELTS to investigate the Martian continental crust hypothesis. The research team concluded that the felsic rocks in Gale Crater do not represent continental crust, as it is defined on Earth.

“We determined that Martian felsic rocks formed via processes not observed at plate boundaries,” Udry said. “Instead, the ‘granite-like’ rocks at Gale Crater formed similar to those formed by ‘hot spot’ volcanoes on Earth, such as those in Hawaii, Iceland, and the Canary Islands.” Granite-like rocks on Mars and within tectonic plates on Earth form through a simple process, called fractional crystallization, which involves formation of crystals during cooling of magma, resulting in changes of magma composition.

Did You Know
The only samples of Mars that we possess on Earth are meteorites. Only 110 Martian meteorites have been classified as such. The Mars2020 mission, which will launch in summer 2020, is planning on returning samples back to Earth in a minimum of 10 years. The landing site for this mission will be voted on in October 2018.